Picking Typefaces by Frank Chimero shows me I can't tell the difference between typefaces.

I actually just recently started using Dank Mono which uses ligatures and am really enjoying it!

I would argue they don't fall into the “solution in search of a problem” camp. The solution here is a way to display an arrow (already solved by =>). Ligatures are a bit of surprise/delight on top of the existing solution. An improvement to UX (for those who enjoy them) as opposed to an entirely new solution.

Still, I can see how they could appear as a little frivolous to some.

@kusters I agree. While they’re a bit of a novelty, I see ligatures as the actual solution finally replacing the combined-characters workaround of the past. One of the most important properties of good code is readability. If using the actual symbols makes code more readable, it’s perfectly valid.

@geewiz @kusters I can buy the "delight" argument. It just doesn't seem to me like the ligatures are any more legible than the separate characters they're replacing, and in some cases are a little less so.

@mdhughes I know some folks definitely like them! But if I can't tell at a glance that "==" is two equals signs and "===" is three, I think "use a font that makes those very distinct characters that don't run into one another," not "use a font that makes them into new zazzy ligatures." :)